This document is the manufacturer stating that its own products cannot be combined on one building. IKO states the two three-tabs cannot be mixed, and gives the reason in performance terms rather than appearance.
Do-not-mix IKO · Roofing · 2023 · 1 page
New vs Old Shingles Compatibility — IKO Marathon Plus AR
In their own words
Cannot be mixed… will affect the water shedding and wind resistance performances.
IKO — New vs Old Shingles Compatibility — IKO Marathon Plus AR, 2023
That sentence is not our characterisation of the manufacturer’s position. It is the manufacturer’s position, in the document below, which you can read yourself in about a minute.
Get the document
New vs Old Shingles Compatibility — IKO Marathon Plus AR
Issued by IKO. Published here complete — no summary standing in for the document, no email required.
Issued by IKO. Held in this firm’s reference library; not published elsewhere. Homeowner-identifying details, where a letter was addressed to a particular property, are blacked out — nothing else is altered, and no operative text is ever redacted.
What to do with it
This is the argument carriers least expect, because it does not come from you. When the manufacturer says two of its own products may not share a roof, a repair that combines them is not a cheaper way of doing the job — it is a defective installation, and the party who directed it owns the outcome.
- You have the manufacturer’s document. That part is finished. Most homeowners never get this far, and it is the step a carrier cannot argue with — it is not your opinion, it is the company that made the product.
- Put it in writing, to the adjuster, with the claim number. Attach the document and ask one specific question: name the exact replacement product — manufacturer, line, colour, dimensions, exposure, nail zone, sealant design, supplier, quantity available locally — and who will answer for the repair if it fails. Vague answers are the whole game; a specific question ends it.
- Get the position on the record before anything gets installed. Once a mismatched or incompatible repair is on the building, you are arguing about something already done.
If you want the second and third steps handled by someone who does this for a living, that is what we are for — and the review costs nothing. If you would rather do it yourself, the document above is yours either way. That is the point of publishing it.
Related documents
Other IKO documents
IKO Cambridge 25
Discontinued in 2001 and dimensionally incompatible with the Cambridge sold today: the old Imperial shingle ran 39 3/16″ × 14¼″ at a 6⅛″ exposure, the current Metric one 40⅞″ × 13¾″ at 5⅞″. IKO also rejects trimming new shingles to fit.
IKO Cambridge
IKO’s Warranty Services Department confirms Cambridge changed dimensions in 2002, making pre- and post-2002 shingles incompatible on the same plane — and that the colours changed too.
IKO Cambridge vs. Dynasty
IKO’s Codes and Compliance Officer on mixing two current IKO products, never mind old and new. IKO also disclaims responsibility where a mixed repair is performed.
IKO Gentry (3-tab)
The Gentry 3-tab (36″ × 12¼″, 5⅛″ exposure) is discontinued with no replacement — IKO no longer manufactures a standard-size three-tab at all. The only three-tab it still makes, Marathon Plus AR (39⅜″ × 13¼″, 5⅝″), is expressly incompatible.
IKO Cambridge · Dynasty · Armourshake · Ultra HP colours
Colourways retired effective 2022: Cambridge Aged Redwood, Dynasty Pacific Rim, Armourshake Western Redwood, H&R 12 Aged Redwood and Pacific Rim, and Ultra HP / Ultra HP IR Aged Redwood — plus low-slope base products.
IKO underlayment laps
IKO requires underlayment to wrap a minimum of 6″ over hips and ridges onto the adjoining slope. A single slope on an IKO roof cannot be replaced in isolation without opening the underlayment on the slopes beside it.
Other manufacturers saying the same thing
Atlas Pinnacle
Three separate dimensional eras of the same product name. Pre-2013 Pinnacle measured 38¼″ × 13⅛″ at a 5⅝″ exposure; 2013–2017 measured 39⅜″ × 14″ at 6″; 2017-on measures 42″ × 14″ at 6″. A “Pinnacle roof” tells you almost nothing until you know which era.
Atlas Pinnacle · StormMaster Shake
Effective July 2, 2013 Atlas changed the dimensions of both lines — from 38¼″ × 13⅛″ to 39⅜″ × 14″ — and stated plainly that the two generations cannot share a roof deck.
Atlas Pinnacle Pristine
Atlas states a do-not-mix condition between the original Pinnacle Pristine and every later version. It no longer manufactures a shingle at a 5⅝″ exposure or 39⅜″ length, and the current HP42 cannot be installed on the earlier roof.
CertainTeed Landmark and related lines
Even where the product name has not changed, CertainTeed identifies three conditions that defeat a partial repair on an aging roof: the older shingles have lost pliability, the granule blend has been reformulated, and lines such as Landmark converted from English to metric dimensions.
The rule this document serves
Your policy promises repair or replacement with material of like kind and quality. That is a replacement-cost and indemnity obligation, not an appearance theory — and it is why “matching” is the carrier’s word, not the policy’s. Where the installed product cannot be bought, or cannot be combined with what is still sold, the covered building cannot be restored to like kind and quality by patching it, and that is true before anyone argues about how it looks. The full doctrine, and the other 125 documents, are on the discontinued materials hub.
You have the manufacturer's document. The next part is the argument. Handing a carrier a technical bulletin and getting it honoured are two different jobs. The case review is free, and you pay nothing unless we recover.
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